An oxygen sensor has been utilized to measure oxygen in exhaust streams. The oxygen sensor has an open channel that allows ambient air to fluidly communicate with a reference electrode. A problem associated with the oxygen sensor recognized by the inventors herein, however, is that the open channel can undesirably allow hydrocarbons to fluidly communicate with the reference electrode that may cause the oxygen sensor to generate a signal that does not accurately indicate an oxygen concentration in exhaust gases communicating with a sensing electrode of the oxygen sensor.
The inventors herein have recognized a need for an improved oxygen sensor that minimizes and/or eliminates the foregoing problem.